For other switch stack-related information, such as cabling the switches through their stack ports and using the LEDs for switch stack status, see the hardware installation guide.

Understanding Stacks

A switch stack is a set of up to four Catalyst 2960-S switches connected through their stack ports. One of the switches controls the operation of the stack and is called the stack master. The stack master and the other switches in the stack are stack members. Layer 2 protocol presents the entire switch stack as a single entity to the network.

Note A switch stack is different from a switch cluster. A switch cluster is a set of switches connected through their LAN ports, such as the 10/100/1000 ports. For more information about how switch stacks differ from switch clusters, see the "Planning and Creating Clusters" chapter in the Getting Started with Cisco Network Assistant on Cisco.com.

The master is the single point of stack-wide management. From the master, you configure:

•System-level (global) features that apply to all members

•Interface-level features for each member

If the stack master is running the cryptographic version (that is, supports encryption) of the software, the encryption features are available.

Every member is uniquely identified by its own stack member number.

All members are eligible masters. If the master becomes unavailable, the remaining members elect a new master from among themselves. One of the factors is the stack member priority value. The switch with the highest stack-member priority-value becomes the master.

The system-level features supported on the master are supported on the entire stack.

The master contains the saved and running configuration files for the stack. The configuration files include the system-level settings for the stack and the interface-level settings for each member. Each member has a current copy of these files for back-up purposes.

You manage the stack through a single IP address. The IP address is a system-level setting and is not specific to the master or to any other member. You can manage the stack through the same IP address even if you remove the master or any other member from the stack.

You can use these methods to manage stacks:

•Network Assistant (available on Cisco.com)

•Command-line interface (CLI) over a serial connection to the console port of any member

Note Use SNMP to manage network features across the stack that are defined by supported MIBs. The switch does not support MIBs to manage stacking-specific features such as stack membership and election.

Stack Membership

Note A switch stack can have only Catalyst 2960-S stack members.

A standalone switch is a stack with one member that is also the master. You can connect one standalone switch to another (Figure 9-1) to create a stack containing two stack members, with one of them as the master. You can connect standalone switches to an existing stack (Figure 9-2) to increase the stack membership.

If you replace a stack member with an identical model, the new switch functions with the same configuration as the replaced switch (assuming that the new switch is using the same member number as the replaced switch). For information about the benefits of provisioning a switch stack, see the "Stack Offline Configuration" section. For information about replacing a failed switch, see the "Troubleshooting" chapter in the hardware installation guide.

The operation of the stack continues uninterrupted during membership changes unless you remove the master or you add powered-on standalone switches or stacks.

Note To prevent interrupted stack operations, make sure the switches that you add to or remove from the stack are powered off.

After adding or removing members, make sure that the stack ring is operating at full bandwidth (20 Gb/s). Press the Mode button on a member until the Stack mode LED is on. The last two port LEDs on all switches in the stack should be green. If any one or both of any the last two port LEDs are not green, the stack is not operating at full bandwidth.

•Adding powered-on switches (merging) causes the masters of the merging stacks to elect a master from among themselves. The new master keeps its role and configuration and so do its members. All remaining switches, including the former masters, reload and join the stack as members. They change their member numbers to the lowest available numbers and use the configuration of the new master.

•Removing powered-on members divides (partitions) the stack into two or more switch stacks, each with the same configuration. This can create an IP address configuration conflict in your network. If you want the stacks to remain separate, change the IP address or addresses of the newly created stacks.

Figure 9-1 Creating a Switch Stack from Two Standalone Switches

1

Standalone switch

3

Stack member 2 and stack master

2

Stack member 1

Figure 9-2 Adding a Standalone Switch to a Switch Stack

1

Stack member 1

4

Stack member 4

2

Stack member 2 and stack master

5

Standalone switch

3

Stack member 3

For information about cabling and powering switch stacks, see the "Switch Installation" chapter in the hardware installation guide.

Master Election

The stack master is elected based on one of these factors in the order listed:

1. The switch that is currently the stack master.

2. The switch with the highest stack member priority value.

Note We recommend you assign the highest priority value to the switch that you want to be the master. The switch is then re-elected as master if a re-election occurs.

In the events marked by an asterisk (*), the current stack master might be re-elected based on the listed factors.

When you power on or reset an entire stack, some stack members might not participate in the master election.

•All members participate in re-elections.

•Members that are powered on within the same 20-second time frame participate in the master election and have a chance to become the master.

•Members that are powered on after the 20-second time frame do not participate in this initial election and only become members.

The new master is available after a few seconds. In the meantime, the switch stack uses the forwarding tables in memory to minimize network disruption. The physical interfaces on the other available stack members are not affected while a new stack master is elected and is resetting.

When a new master is elected and the previous stack master becomes available, the previous master does not resume its role as stack master.

For all powering considerations that affect stack-master elections, see the "Switch Installation" chapter in the hardware installation guide.

Stack MAC Address

The MAC address of the master determines the stack MAC address.

When the stack initializes, the MAC address of the master determines the bridge ID that identifies the stack in the network.

If the master changes, the MAC address of the new master determines the new bridge ID. However, when the persistent MAC address feature is enabled, there is an approximate 4-minute delay before the stack MAC address changes. During this time period, if the previous master rejoins the stack, the stack continues to use its MAC address as the stack MAC address, even if the switch is now a member and not a master. If the previous master does not rejoin the stack during this period, the stack takes the MAC address of the new stack master as the stack MAC address. See the "Enabling Persistent MAC Address" section for more information.

Member Numbers

The member number (1 to 4) identifies each member in the stack. The member number also determines the interface-level configuration that a member uses.

A new, out-of-the-box switch (one that has not joined a stack or has not been manually assigned a member number) ships with a default member number of 1. When it joins a stack, its default stack member number changes to the lowest available member number in the stack.

Members in the same stack cannot have the same member number.

•If you manually change the member number by using the switch current-stack-member-number renumber new-stack-member-number global configuration command, the new number goes into effect after that member resets (or after you use the reload slot stack-member-number privileged EXEC command) and only if that number is not already changed.

You can also change the stack member number is by using the SWITCH_NUMBER environment variable.

If the number is being used by another member in the stack, the switch selects the lowest available number in the stack.

If you manually change the member number and no interface-level configuration is associated with that number, that member resets to its default configuration.

You cannot use the switch current-stack-member-number renumber new-stack-member-number global configuration command on a provisioned switch. If you do, the command is rejected.

•If you move a stack member to a different switch stack, the stack member keeps its number only if the number is not being used by another member in the stack. If it is being used by another member in the stack, the switch selects the lowest available number in the stack.

See the following sections for information about stack member configuration:

Member Priority Values

A high priority value for a member increases the chance that it will be elected master and keep its member number. The priority value can be 1 to 15. The default priority value is 1.

Note We recommend that you assign the highest priority value to the switch that you want to be the stack master. The switch is then re-elected as master if a re-election occurs.

The new priority value takes effect immediately but does not affect the current master until the current master or the stack resets.

Stack Offline Configuration

You can use the offline configuration feature to provision (to configure) a new switch before it joins the stack. You can configure the member number, the switch type, and the interfaces associated with a switch that is not yet part of the stack. That configuration is the provisioned configuration. The switch to be added to the stack and to get this configuration is the provisioned switch.

The provisioned configuration is automatically created when a switch is added to a stack and when no provisioned configuration exists. You can manually create the provisioned configuration by using the switchstack-member-numberprovisiontype global configuration command.

When you configure the interfaces for a provisioned switch (for example, as part of a VLAN), the information appears in the stack running configuration whether or not the provisioned switch is part of the stack. The interface for the provisioned switch is not active and does not appear in the display of a specific feature (for example, in the show vlan user EXEC command output). Entering the no shutdown interface configuration command has no effect.

The startup configuration file ensures that the stack can reload and can use the saved information whether or not the provisioned switch is part of the stack.

Effects of Adding a Provisioned Switch to a Stack

When you add a provisioned switch to the switch stack, the stack applies either the provisioned configuration or the default configuration to it. Table 9-1 lists the events that occur when the switch stack compares the provisioned configuration with the provisioned switch.

Table 9-1 Results of Comparing the Provisioned Configuration with the Provisioned Switch

Scenario

Result

The stack member numbers and the switch types match.

1. If the stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, and

2. If the switch type of the provisioned switch matches the switch type in the provisioned configuration on the stack.

The switch stack applies the provisioned configuration to the provisioned switch and adds it to the stack.

The stack member numbers match but the switch types do not match.

1. If the stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, but

2. The switch type of the provisioned switch does not match the switch type in the provisioned configuration on the stack.

The switch stack applies the default configuration to the provisioned switch and adds it to the stack.

The provisioned configuration is changed to reflect the new information.

The stack member number is not found in the provisioned configuration.

The switch stack applies the default configuration to the provisioned switch and adds it to the stack.

The provisioned configuration is changed to reflect the new information.

The stack member number of the provisioned switch is in conflict with an existing stack member.

The stack master assigns a new stack member number to the provisioned switch.

The stack member numbers and the switch types match:

1. If the new stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, and

2. If the switch type of the provisioned switch matches the switch type in the provisioned configuration on the stack.

The switch stack applies the provisioned configuration to the provisioned switch and adds it to the stack.

The provisioned configuration is changed to reflect the new information.

The stack member numbers match, but the switch types do not match:

1. If the stack member number of the provisioned switch matches the stack member number in the provisioned configuration on the stack, but

2. The switch type of the provisioned switch does not match the switch type in the provisioned configuration on the stack.

The switch stack applies the default configuration to the provisioned switch and adds it to the stack.

The provisioned configuration is changed to reflect the new information.

The stack member number of the provisioned switch is not found in the provisioned configuration.

The switch stack applies the default configuration to the provisioned switch and adds it to the stack.

If you add a provisioned switch that is a different type than specified in the provisioned configuration to a powered-down switch stack and then apply power, the switch stack rejects the (now incorrect) switchstack-member-numberprovisiontype global configuration command in the startup configuration file. However, during stack initialization, the nondefault interface configuration information in the startup configuration file for the provisioned interfaces (potentially of the wrong type) are executed. Depending on how different the actual switch type is from the previously provisioned switch type, some commands are rejected, and some commands are accepted.

Note If the switch stack does not contain a provisioned configuration for a new switch, the switch joins the stack with the default interface configuration. The switch stack then adds to its running configuration a switchstack-member-numberprovisiontype global configuration command that matches the new switch.

Effects of Replacing a Provisioned Switch in a Stack

When a provisioned switch in a switch stack fails, is removed from the stack, and is replaced with another switch, the stack applies either the provisioned configuration or the default configuration to it. The events that occur when the switch stack compares the provisioned configuration with the provisioned switch are the same as those described in the "Effects of Adding a Provisioned Switch to a Stack" section.

Effects of Removing a Provisioned Switch from a Stack

If you remove a provisioned switch from the switch stack, the configuration associated with the removed stack member remains in the running configuration as provisioned information. To completely remove the configuration, use the no switchstack-member-numberprovision global configuration command.

Stack Software Compatibility Recommendations

All stack members must run the same Cisco IOS software version to ensure compatibility in the stack protocol version among the members.

Stack Protocol Version Compatibility

The stack protocol version has a major version number and a minor version number (for example 1.4, where 1 is the major version number and 4 is the minor version number).

Switches with the same Cisco IOS software version have the same stack protocol version. All features function properly across the stack. These switches with the same software version as the master immediately join the stack.

If an incompatibility exists, a system message describes the cause of the incompatibility on the specific stack members. The master sends the message to all members.

Major Version Number Incompatibility Among Switches

Switches with different Cisco IOS software versions likely have different stack protocol versions. Switches with different major version numbers are incompatible and cannot exist in the same stack.

Minor Version Number Incompatibility Among Switches

Switches with the same major version number but with a different minor version number as the master are considered partially compatible. When connected to a stack, a partially compatible switch enters version-mismatch mode and cannot join the stack as a fully functioning member. The software detects the mismatched software and tries to upgrade (or downgrade) the switch in version-mismatch mode with the stack image or with a tar file image from the stack flash memory. The software uses the automatic upgrade (auto-upgrade) and the automatic advise (auto-advise) features.

The port LEDs on switches in version-mismatch mode will also stay off. Pressing the Mode button does not change the LED mode.

Note Auto-advise and auto-copy identify which images are running by examining the info file and by searching the directory structure on the switch stack. If you download your image by using the copy tftp: command instead of by using the archive download-sw privileged EXEC command, the correct directory structure is not properly created. For more information about the info file, see the "tar File Format of Images on a Server or Cisco.com" section.

Understanding Auto-Upgrade and Auto-Advise

When the software detects mismatched software and tries to upgrade the switch in version-mismatch mode, two software processes are involved: automatic upgrade and automatic advise.

•The automatic upgrade (auto-upgrade) process includes an auto-copy process and an auto-extract process. By default, auto-upgrade is enabled (the boot auto-copy-sw global configuration command is enabled). You can disable auto-upgrade by using the no boot auto-copy-sw global configuration command on the master. You can check the status of auto-upgrade by using the show boot privileged EXEC command and by checking the Auto upgrade line in the display.

–Auto-copy automatically copies the software image running on any member to the switch in version-mismatch mode to upgrade (auto-upgrade) it. Auto-copy occurs if auto-upgrade is enabled, if there is enough flash memory in the switch in version-mismatch mode, and if the software image running on the stack is suitable for the switch in version-mismatch mode.

Note A switch in version-mismatch mode might not run all released software. For example, new switch hardware is not recognized in earlier versions of software.

–Automatic extraction (auto-extract) occurs when the auto-upgrade process cannot find the appropriate software in the stack to copy to the switch in version-mismatch mode. In that case, the auto-extract process searches all switches in the stack, whether they are in version-mismatch mode or not, for the tar file needed to upgrade the switch stack or the switch in version-mismatch mode. The tar file can be in any flash file system in the stack (including the switch in version-mismatch mode). If a tar file suitable for the switch in version-mismatch mode is found, the process extracts the file and automatically upgrades that switch.

The auto-upgrade (auto-copy and auto-extract) processes start a few minutes after the mismatched software is detected.

When the auto-upgrade process is complete, the switch that was in version-mismatch mode reloads and joins the stack as a fully functioning member. If you have both stack cables connected during the reload, network downtime does not occur because the stack operates on two rings.

•Automatic advise (auto-advise)—when the auto-upgrade process cannot find appropriate version-mismatch member software to copy to the switch in version-mismatch mode, the auto-advise process tells you the command (archive copy-sw or archive download-sw privileged EXEC command) and the image name (tar filename) needed to manually upgrade the switch stack or the switch in version-mismatch mode. The recommended image can be the running stack image or a tar file in any flash file system in the stack (including the switch in version-mismatch mode). If an appropriate image is not found in the stack flash file systems, the auto-advise process tells you to install new software on the stack. Auto-advise cannot be disabled, and there is no command to check its status.

The auto-advise software does not give suggestions when the stack software and the software of the switch in version-mismatch mode do not contain the same feature sets.The same events occur when cryptographic and noncryptographic images are running.

You can use the archive-download-sw /allow-feature-upgrade privileged EXEC command to allow installing an image with a different feature set.

Auto-Upgrade and Auto-Advise Example Messages

When you add a switch that has a different minor version number to the stack, the software displays messages in sequence (assuming that there are no other system messages generated by the switch).

This example shows that the stack detected a new switch that is running a different minor version number than the stack. Auto-copy launches, finds suitable software to copy from a member to the switch in version-mismatch mode, upgrades the switch in version-mismatch mode, and then reloads it:

*Mar 11 20:31:19.247:%STACKMGR-6-STACK_LINK_CHANGE:Stack Port 2 Switch 2 has changed to
state UP

*Mar 11 20:31:23.232:%STACKMGR-6-SWITCH_ADDED_VM:Switch 1 has been ADDED to the stack
(VERSION_MISMATCH)

*Mar 11 20:31:23.291:%STACKMGR-6-SWITCH_ADDED_VM:Switch 1 has been ADDED to the stack
(VERSION_MISMATCH) (Stack_1-3)

This example shows that the stack detected a new switch that is running a different minor version number than the stack. Auto-copy launches but cannot find software in the stack to copy to the switch in version-mismatch mode to make it compatible with the stack. The auto-advise process launches and recommends that you download a tar file from the network to the switch in version-mismatch mode:

*Mar 1 00:01:11.319:%STACKMGR-6-STACK_LINK_CHANGE:Stack Port 2 Switch 2 has changed to
state UP

*Mar 1 00:01:15.547:%STACKMGR-6-SWITCH_ADDED_VM:Switch 1 has been ADDED to the stack
(VERSION_MISMATCH)

Incompatible Software and Member Image Upgrades

You can upgrade a switch that has an incompatible software image by using the archive copy-sw privileged EXEC command to copy the software image from an existing member. That switch automatically reloads with the new image and joins the stack as a fully functioning member.

Stack Configuration Files

The master has the saved and running configuration files for the stack. All members periodically receive synchronized copies of the configuration files from the master. If the master becomes unavailable, any member assuming the role of master has the latest configuration files.

•System-level (global) configuration settings—such as IP, STP, VLAN, and SNMP settings—that apply to all members

•Member interface-specific configuration settings, which are specific for each member

A new, out-of-box switch joining a stack uses the system-level settings of that stack. If a switch is moved to a different stack, it loses its saved configuration file and uses the system-level configuration of the new stack.

The interface-specific configuration of each member is associated with its member number. A stack member keeps its number unless it is manually changed or it is already used by another member in the same stack.

•If an interface-specific configuration does not exist for that member number, the member uses its default interface-specific configuration.

•If an interface-specific configuration exists for that member number, the member uses the interface-specific configuration associated with that member number.

If you replace a failed member with an identical model, the replacement member automatically uses the same interface-specific configuration. You do not need to reconfigure the interface settings. The replacement switch must have the same member number as the failed switch.

You back up and restore the stack configuration in the same way as you do for a standalone switch configuration.

Stack Management Connectivity

You manage the stack and the member interfaces through the master. You can use the CLI, SNMP, Network Assistant, and CiscoWorks network management applications. You cannot manage members as individual switches.

Stack Through an IP Address

The stack is managed through a system-level IP address. You can still manage the stack through the same IP address even if you remove the master or any other stack member from the stack, provided there is IP connectivity.

Note Members keep their IP addresses when you remove them from a stack. To avoid having two devices with the same IP address in your network, change the IP address of the switch that you removed from the stack.

Stack Through an SSH Session

The Secure Shell (SSH) connectivity to the stack can be lost if a master running the cryptographic version fails and is replaced by a switch that is running a noncryptographic version. We recommend that a switch running the cryptographic version of the software be the master.

Stack Through Console Ports

You can connect to the master through the console port of one or more members.

Be careful when using multiple CLI sessions to the master. Commands that you enter in one session are not displayed in the other sessions. Therefore, it is possible that you might not be able to identify the session from which you entered a command.

We recommend that you use only one CLI session when managing the stack.

Specific Members

If you want to configure a specific member port, you must include the stack member number in the CLI notation.

Stack Configuration Scenarios

Most of the scenarios in Table 9-2 assume at least two switches are connected through their stack ports.

Table 9-2 Switch Stack Configuration Scenarios

Scenario

Result

Master election specifically determined by existing masters

Connect two powered-on stacks through the stack ports.

Only one of the two masters becomes the new stack master.

Master election specifically determined by the member priority value

1. Connect two switches through their stack ports.

2. Use the switch stack-member-number priority new-priority-number global configuration command to set one member with a higher member priority value.

3. Restart both members at the same time.

The member with the higher priority value is elected master.

Master election specifically determined by the configuration file

Assuming that both members have the same priority value:

1. Make sure that one member has a default configuration and that the other member has a saved (nondefault) configuration file.

2. Restart both members at the same time.

The member with the saved configuration file is elected master.

Master election specifically determined by the MAC address

Assuming that both members have the same priority value, configuration file, and software image, restart both stack members at the same time.

The member with the lower MAC address is elected master.

Member number conflict

Assuming that one member has a higher priority value than the other member:

1. Ensure that both members have the same member number. If necessary, use the switch current-stack-member-number renumber new-stack-member-number global configuration command.

2. Restart both members at the same time.

The member with the higher priority value keeps its member number. The other member has a new stack member number.

Add a member

1. Power off the new switch.

2. Through their stack ports, connect the new switch to a powered-on stack.

3. Power on the new switch.

The master is kept. The new switch is added to the stack.

Master failure

Remove (or power off) the master.

One of the remaining stack members becomes the new master. All other members in the stack remain members and do not restart.

Add more than four members

1. Through their stack ports, connect ten switches.

2. Power on all switches.

Two switches become masters. One master has four stack members. The other master remains a standalone switch.

Use the Mode button and port LEDs on the switches to identify which switches are masters and which switches belong to each master. For information about the Mode button and the LEDs, see the hardware installation guide.

Enabling Persistent MAC Address

The MAC address of the master determines the stack MAC address. When a master is removed from the stack and a new master takes over, the MAC address of the new master to become the new stack MAC address. However, you can set the persistent MAC address feature with a time delay before the stack MAC address changes. During this time period, if the previous master rejoins the stack, the stack continues to use that MAC address as the stack MAC address, even if the switch is now a member and not a master. You can also configure stack MAC persistency so that the stack MAC address never changes to the new master MAC address.

Caution When you configure this feature, a warning message displays the consequences of your configuration. You should use this feature cautiously. Using the old master MAC address elsewhere in the domain could result in lost traffic.

You can set the time period from 0 to 60 minutes.

•If you enter the command with no value, the default delay is 4 minutes. We recommend that you always enter a value. The time delay appears in the configuration file with an explicit timer value of 4 minutes.

•If you enter 0, the stack MAC address of the previous master is used until you enter the no stack-mac persistent timer global configuration command, which changes the stack MAC address to that of the current master. If you do not enter this command, the stack MAC address does not change.

•If you enter a time delay of 1 to 60 minutes, the stack MAC address of the previous master is used until the configured time period expires or until you enter the no stack-mac persistent timer command.

If the previous master does not rejoin the stack during this period, the stack uses the MAC address of the new master as the stack MAC address.

Note If the entire switch stack reloads, it acquires the MAC address of the master as the stack MAC address.

Enable a time delay after a stack-master change before the stack MAC address changes to that of the new stack master. If the previous stack master rejoins the stack during this period, the stack uses that MAC address as the stack MAC address.

•Enter the command with no value to set the default delay of 4 minutes. We recommend that you always configure a value.

•Enter 0 to use the MAC address of the current master indefinitely.

•Enter a time-value from 1 to 60 to configure the time period (in minutes) before the stack MAC address changes to the new master.

Caution When you enter this command, a warning states that traffic might be lost if the old master MAC address appears elsewhere in the network domain.

If you enter the no stack-mac persistent timer command after a new stack master takes over, before the time expires, the stack uses the current master MAC address.

Step 3

end

Return to privileged EXEC mode.

Step 4

show running-config

or

show switch

Verify that the stack MAC address timer is enabled.

The output shows stack-mac persistent timer and the time in minutes.

The output shows Mac persistency wait time with the number of minutes configured and the stack MAC address.

Step 5

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no stack-mac persistent timer global configuration command to disable the persistent MAC address feature. This example shows how to configure the persistent MAC address feature for a 7-minute time delay and to verify the configuration:

Provisioning a New Member for a Stack

Beginning in privileged EXEC mode, follow these steps to provision a new member for a stack. This procedure is optional.

Command

Purpose

Step 1

show switch

Display summary information about the stack.

Step 2

configure terminal

Enter global configuration mode.

Step 3

switchstack-member-number provisiontype

Specify the member number for the provisioned switch. By default, no switches are provisioned.

For stack-member-number, the range is 1 to 4. Enter a member number that is not already used in the stack. See Step 1.

For type, enter the model number of the member.

Step 4

end

Return to privileged EXEC mode.

Step 5

show running-config

Verify the correct numbering of interfaces in the configuration.

Step 6

show switchstack-member-number

Verify the status of the provisioned switch. For stack-member-number, enter the same number as in Step 2.

Step 7

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To remove provisioned information and to avoid receiving an error message, remove the specified switch from the stack before you use the no form of this command.

This example shows how to provision a switch with a stack member number of 2 for the stack. The show running-config command output shows the interfaces associated with the provisioned switch:

Switch(config)# switch 2 provision switch PID

Switch(config)# end

Switch# show running-config | include switch 2

!

interface GigabitEthernet2/0/1

!

interface GigabitEthernet2/0/2

!

interface GigabitEthernet2/0/3

<output truncated>

Changing the Stack Membership

If you remove powered-on members but do not want to partition the stack:

Step 1 Power off the newly created stacks.

Step 2 Reconnect them to the original stack through their stack ports.

Step 3 Power on the switches.

Accessing the CLI of a Specific Member

Note This task is only for debugging purposes, and is only available from the master.

You can access all or specific members by using the remote command {all | stack-member-number} privileged EXEC command. The stack member number range is 1 to 4.

You can access specific members by using the sessionstack-member-number privileged EXEC command. The member number is appended to the system prompt. For example, the prompt for member 2 is Switch-2#, and system prompt for the master is Switch#. Enter exit to return to the CLI session on the master. Only the show and debug commands are available on a specific member.

Troubleshooting Stacks

Manually Disabling a Stack Port

If a stack port is flapping and causing instability in the stack ring, to disable the port, enter the switchstack-member-number stack port port-numberdisable privileged EXEC command. To re-enable the port, enter the switchstack-member-number stack port port-numberenable command.

Note Be careful when using the switchstack-member-number stack port port-numberdisable command. When you disable the stack port, the stack operates at half bandwidth.

•A stack is in the full-ring state when all members are connected through the stack ports and are in the ready state.

•The stack is in the partial-ring state when

–All members are connected through the stack ports, but some all are not in the ready state.

–Some members are not connected through the stack ports.

When you enter the switchstack-member-number stack port port-numberdisable privileged EXEC command and

•The stack is in the full-ring state, you can disable only one stack port. This message appears: